Hi mam...    Usually toothache occurs when the caries reaches the pulp layer(Deep layer which contains nerves).... Root canal treatment is the CONSERVATIVE TREATMENT which will remove the infected pulp(nerve layer) by making hole in the coronal portion of tooth.... By doing root canal one can save the natural tooth structure  which will be esthetoc and used for mastication and speech.. Other than root canal the only option available is Extraction of the involved teeth... Extraction is not a conservative process, if you fail to fix the extracted tooth region with artificial teeth it will weekens the 3 nearby tooth of the extracted site... The adjacent teeth will migrate in the edentulous space and the tooth in the opposite arch also supraerupts and cause space closure.. First and foremost x_ray(IOPA) should be taken to rule out the extent of caries.... According to radiographic investigation,treatlent option should be made..

Only if the cavity is very deep involving the nerve ( pulp) of the tooth. Otherwise just a filling is sufficient